Effect of Cardiopulmonary Bypass on Blood Lactate Level in Patients Undergoing Single Valve Replacement: A Prospective Observational Study

Background Cardiopulmonary bypass allows surgeons to replace a diseased valve in a bloodless and still heart. It, however, tends to increase the blood lactate level with resultant adverse effects. Our study aimed to investigate its effects on blood lactate level. Data and Methods A prospective observational study was conducted in 41 patients undergoing single heart valve replacement at Manmohan Cardiothoracic Vascular and Transplant Center from August, 2023 to November, 2023. Arterial blood lactate concentration was measured pre-operatively, after 15 minutes of cardiopulmonary bypass initiation, 12 and 24 hours post-operatively. Other parameters studied were age, gender, hypertension, diabetes, perfusion pressure, aortic cross clamp and bypass time, complications or mortality. Results Mean lactate levels were found to be 1.45±0.55mmol/L, 2.05±0.70mmol/L, 5.40±2.07mmol/L and 2.91±1.11mmol/L preoperatively, intraoperatively, 12 and 24 hours postoperatively, respectively. Patients with higher mean lactate level had significantly longer aortic cross clamp and bypass time and lower perfusion pressure. No relation between peak lactate change and mortality was observed. The patients’ age, gender, hypertension and diabetes were not found to be significantly affecting peak lactate change during surgery. Conclusion Aortic cross clamp time, bypass time and perfusion pressure are significant predictive factors for peak lactate change during surgery. Key Words: Cardiopulmonary bypass, hyperlactatemia, valve replacement